Congenital adrenal hyperplasia (CAH) is caused by an enzyme defect in the adrenal steroid biosynthetic pathway. This disease is managed primarily by glucocorticoid replacement therapy, but the appropriate therapeutic range is narrow and changes over time. Under-treatment leads to excess adrenal androgen production with consequent adverse effects, including hirsutism, virilization, early puberty, and short stature. Over-treatment causes direct growth suppression and appetite stimulation with consequent adverse effects of short stature and obesity. The hypothesis for this study is that fingerstick bloodspot 17-OH-P can be a useful assessment of adequacy of therapy for CAH. This study will involve hourly measurement of the venous blood 17-OH-P of patients with CAH on their usual dose of replacement adrenal steroids. The patients will be assessed objectively by urinary pregnanetriol measurements with substantiation by history, physical exam, and other adrenal hormone assays to determine whether each patient is being optimally treated or over-treated or under-treated.